Numerical Investigation on the Effect of Spectral Radiative Heat Transfer within an Ablative Material

The spectral radiative heat flux could impact the material response. In order to evaluate it, a coupling scheme between KATS - MR and P1 approximation model of radiation transfer equation (RTE) is constructed and used. A Band model is developed that divides the spectral domain into small bands of unequal widths. Two verification studies are conducted: one by comparing the simulation computed by the Band model with pure conduction results and the other by comparing with similar models of RTE. The comparative results from the verification studies indicate that the Band model is computationally efficient and can be used to simulate the material\u27s response when exposed to spectral radiative heat flux. To further evaluate the effectiveness of the spectral form of heat transfer, material response simulations were run by taking into account spectral data as the boundary condition. The results indicate a significant difference in temperature and density distributions within the sample. The internal temperatures are predicted higher with early decomposition when the spectral radiative heat flux is considered

Fully Coupled Internal Radiative Heat Transfer for the 3D Material Response of Heat Shield

The radiative transfer equation (RTE) is strongly coupled to the material response code KATS. A P-1 approximation model of RTE is used to account for radiation heat transfer within the material. First, the verification of the RTE model is performed by comparing the numerical and analytical solutions. Next, the coupling scheme is validated by comparing the temperature profiles of pure conduction and conduction coupled with radiative emission. The validation study is conducted on Marschall et al. cases (radiant heating, arc-jet heating, and space shuttle entry), 3D Block, 2D IsoQ sample, and Stardust Return Capsule. The validation results agree well for all the cases within a margin of error of 10%. Thus, the validation results indicate that the coupling approach can simulate the thermal response of material accurately. The coupling scheme is then used to simulate a laser heating experiment that studied the impact of spectral radiate heat transfer on ablative material. The results from the laser ablation simulations indicate the expected behavior and match well with experimental ones implying the effect of spectral radiative flux on the material response

Numerical Reconstruction of Spalled Particle Trajectories in an Arc-Jet Environment

To evaluate the effects of spallation on ablative material, it is necessary to evaluate the mass loss. To do so, a Lagrangian particle trajectory code is used to reconstruct trajectories that match the experimental data for all kinematic parameters. The results from spallation experiments conducted at the NASA HYMETS facility over a wedge sample were used. A data-driven adaptive methodology was used to adapts the ejection parameters until the numerical trajectory matches the experimental data. The preliminary reconstruction results show that the size of the particles seemed to be correlated with the location of the ejection event. The size of the particles ejected from the bottom edge of the wedge varies over three orders of magnitude, whereas the size of the ones ejected from the top (inclined) surface were more uniform (around 10 microns). On the bottom edge, the particles ejected near the leading edge were bulkier (10-1000 microns), where those that ejected further along, had a smaller size (0.1-1 microns)

What is the suitability of clinical vignettes in benchmarking the performance of online symptom checkers? An audit study

Objective: Assess the suitability of clinical vignettes in benchmarking the performance of online symptom checkers (OSCs). Design: Observational study using a publicly available free OSC. Participants: Healthily OSC, which provided consultations in English, was used to record consultation outcomes from two lay and four expert inputters using 139 standardised patient vignettes. Each vignette included three diagnostic solutions and a triage recommendation in one of three categories of triage urgency. A panel of three independent general practitioners interpreted the vignettes to arrive at an alternative set of diagnostic and triage solutions. Both sets of diagnostic and triage solutions were consolidated to arrive at a final consolidated version for benchmarking. Main outcome measures: Six inputters simulated 834 standardised patient evaluations using Healthily OSC and recorded outputs (triage solution, signposting, and whether the correct diagnostic solution appeared first or within the first three differentials). We estimated Cohen’s kappa to assess how interpretations by different inputters could lead to divergent OSC output even when using the same vignette or when compared with a separate panel of physicians. Results: There was moderate agreement on triage recommendation (kappa=0.48), and substantial agreement on consultation outcomes between all inputters (kappa=0.73). OSC performance improved significantly from baseline when compared against the final consolidated diagnostic and triage solution (p<0.001). Conclusions: Clinical vignettes are inherently limited in their utility to benchmark the diagnostic accuracy or triage safety of OSC. Real-world evidence studies involving real patients are recommended to benchmark the performance of OSC against a panel of physicians

Randomized trial of peppermint gel, lanolin ointment, and placebo gel to prevent nipple crack in primiparous breastfeeding women

Background: Sore nipples are common during lactation and remain the major reason for failing to establish successful breastfeeding. To formulate a peppermint gel and to evaluate its effect on the prevention of nipple crack associated with breast-feeding, a randomized double-blinded clinical trial comparing the above formulation with modified lanolin and a neutral ointment was carried out. Material/Methods: Two hundred and sixteen primiparous participants were assigned randomly to three groups. Each group applied only one of the above three preparations on both breasts for 14 days. Each group consisted of 72 primiparous mothers and was seen for a maximum of four follow-up visits within 14 days and a final visit at week 6. The rate of nipple and areola crack and pain was evaluated. Results: The study groups were comparable in mean age and route of delivery. Nipple crack were less in mothers who received peppermint gel than in those who received lanolin ointment or placebo (?2=16.8, df=6, P=0.01). Relative risk of nipple crack in the lanolin group (RR: 2.41, 95%CI: 1.20–3.01) was higher than in the peppermint group (RR: 1.85, 95%CI: 1.64–3.10). Conclusions: Prophylactic peppermint gel in breastfeeding lactating women is associated with fewer nipple cracks and is more effective than lanolin and placebo. It could be recommended for preventing of nipple crack along with teaching better breastfeeding technique at the initiation of breastfeedin

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We present a novel approach for deriving analytical solutions to transport equations expressed in similarity variables. We apply a fixed-point iteration procedure to these transformed equations by formally solving for the highest derivative term and then integrating to obtain an expression for the solution in terms of a previous estimate. We are able to analytically obtain the Lipschitz condition for this iteration procedure and, from this (via requirements for convergence given by the contraction mapping principle), deduce a range of values for the outer limit of the solution domain, for which the fixed-point iteration is guaranteed to converge

A Pilot Randomized Clinical Trial of an Enhanced Pivotal Response Treatment Approach for Young Children with Autism: The PRISM Model.

The symptoms of autism spectrum disorder are conceptualized to alter the quality of parent-children interactions, exposure to social learning exchanges, and ultimately the course of child development. There is evidence that modifying the procedures of Pivotal Response Treatment (PRT) to explicitly target social motivation enhances child engagement and parent-child synchrony in moment-by-moment exchanges. However, it is unclear if these within session improvements ultimately yield favorable developmental outcomes over time. The current investigation presents feasibility, utility, and preliminary efficacy data of a pilot randomized clinical trial (RCT) of a Pivotal Response Intervention for Social Motivation (PRISM) model. Data on participant factors, treatment protocol acceptability, and outcome variance and effect size are highly favorable and support the pursuit of a future, large scale RCT